diff --git a/public/course/lib.php b/public/course/lib.php
index 508a5ded148..a7add6de71e 100644
--- a/public/course/lib.php
+++ b/public/course/lib.php
@@ -746,6 +746,8 @@ function course_delete_module($cmid, $async = false) {
             "Cannot delete this module as the file mod/$modulename/lib.php is missing.");
     }
 
+    // Warning! there is very similar code in remove_course_contents.
+    // If you are changing this code, you probably need to change that too.
     $deleteinstancefunction = $modulename . '_delete_instance';
 
     // Ensure the delete_instance function exists for this module.
@@ -774,6 +776,9 @@ function course_delete_module($cmid, $async = false) {
             "Cannot delete the module $modulename (instance).");
     }
 
+    // We delete the questions after the activity database is removed,
+    // because questions are referenced via question reference tables
+    // and cannot be deleted while the activities that use them still exist.
     question_delete_activity($cm);
 
     // Remove all module files in case modules forget to do that.
diff --git a/public/lib/moodlelib.php b/public/lib/moodlelib.php
index c3e44f9dfbf..b528e9543b0 100644
--- a/public/lib/moodlelib.php
+++ b/public/lib/moodlelib.php
@@ -4834,16 +4834,8 @@ function remove_course_contents($courseid, $showfeedback = true, ?array $options
 
             if ($instances) {
                 foreach ($instances as $cm) {
-                    if ($cm->id) {
-                        // Delete activity context questions and question categories.
-                        question_delete_activity($cm, coursedeletion: $coursedeletion);
-                        // Notify the competency subsystem.
-                        \core_competency\api::hook_course_module_deleted($cm);
-
-                        // Delete all tag instances associated with the instance of this module.
-                        core_tag_tag::delete_instances("mod_{$modname}", null, context_module::instance($cm->id)->id);
-                        core_tag_tag::remove_all_item_tags('core', 'course_modules', $cm->id);
-                    }
+                    // Warning! there is very similar code in course_delete_module.
+                    // If you are changing this code, you probably need to change that too.
                     if (function_exists($moddelete)) {
                         // This purges all module data in related tables, extra user prefs, settings, etc.
                         $moddelete($cm->modinstance);
@@ -4854,6 +4846,16 @@ function remove_course_contents($courseid, $showfeedback = true, ?array $options
                     }
 
                     if ($cm->id) {
+                        // Delete activity context questions and question categories.
+                        // We delete the questions after the activity database is removed,
+                        // because questions are referenced via question reference tables
+                        // and cannot be deleted while the activities that use them still exist.
+                        question_delete_activity($cm, coursedeletion: $coursedeletion);
+                        // Delete all tag instances associated with the instance of this module.
+                        core_tag_tag::delete_instances("mod_{$modname}", null, context_module::instance($cm->id)->id);
+                        core_tag_tag::remove_all_item_tags('core', 'course_modules', $cm->id);
+                        // Notify the competency subsystem.
+                        \core_competency\api::hook_course_module_deleted($cm);
                         // Delete cm and its context - orphaned contexts are purged in cron in case of any race condition.
                         context_helper::delete_instance(CONTEXT_MODULE, $cm->id);
                         $DB->delete_records('course_modules_completion', ['coursemoduleid' => $cm->id]);
diff --git a/public/mod/quiz/tests/lib_test.php b/public/mod/quiz/tests/lib_test.php
index 1cdde5fa2b0..d9fb41f37da 100644
--- a/public/mod/quiz/tests/lib_test.php
+++ b/public/mod/quiz/tests/lib_test.php
@@ -139,6 +139,47 @@ final class lib_test extends \advanced_testcase {
         $this->assertEquals(0, $DB->count_records('question_set_references', ['usingcontextid' => $context->id]));
     }
 
+    /**
+     * Test deleting a quiz when the course is deleted.
+     *
+     * @covers ::quiz_delete_instance
+     */
+    public function test_quiz_when_delete_course(): void {
+        global $DB, $USER;
+
+        $this->resetAfterTest();
+        $this->setAdminUser();
+
+        // Step 1: Create one course and a user with editing teacher capabilities.
+        $generator = $this->getDataGenerator();
+        $course = $generator->create_course();
+        $teacher = $USER;
+        $generator->enrol_user($teacher->id, $course->id, 'editingteacher');
+
+        // Create a quiz with questions in the first course.
+        $quiz = $this->create_test_quiz($course);
+        $context = \context_module::instance($quiz->cmid);
+        // Create questions.
+        $questiongenerator = $this->getDataGenerator()->get_plugin_generator('core_question');
+        $cat = $questiongenerator->create_question_category(['contextid' => $context->id]);
+        $saq = $questiongenerator->create_question('shortanswer', null, ['category' => $cat->id]);
+
+        // Add to the quiz.
+        quiz_add_quiz_question($saq->id, $quiz);
+        // Delete the course.
+        delete_course($course, false);
+
+        // Check that the question was deleted.
+        $this->assertFalse($DB->record_exists('question', ['id' => $saq->id]));
+        // Check that all the slots were removed.
+        $this->assertFalse($DB->record_exists('quiz_slots', ['quizid' => $quiz->id]));
+        // Check that the quiz was removed.
+        $this->assertFalse($DB->record_exists('quiz', ['id' => $quiz->id]));
+        // Check that any question references linked to this quiz are gone.
+        $this->assertFalse($DB->record_exists('question_references', ['usingcontextid' => $context->id]));
+        $this->assertFalse($DB->record_exists('question_set_references', ['usingcontextid' => $context->id]));
+    }
+
     public function test_quiz_get_user_attempts(): void {
         global $DB;
         $this->resetAfterTest();